If you haven't entered any JS code, try a full flash erase (erase_flash option, I believe in esptool.py).
@tve started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
If you haven't entered any JS code, try a full flash erase (erase_flash option, I believe in esptool.py).